Shock-resistant backplane utilizing infrared communication scheme with electrical interface for embedded systems

ABSTRACT

Infrared communications scheme for use in an embedded system. According to a preferred embodiment, the invention comprises the use of an infrared communications scheme, according to IrDA protocol, which is utilized to transmit and receive data via an electrical interface between circuit cards housed within an enclosed, embedded system. Preferably, each respective circuit card is provided with a digital tri-stateable transmitter element and a digital receiver to respectively transmit and receive data. The systems and methods of the present invention provide increased reliability than prior-art systems and methods.

STATEMENT OF GOVERNMENT RIGHTS

This invention was made with Government Support under contractN66001-98-C-8518 awarded by the United States Navy. The Government hascertain rights in this invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

(Not Applicable)

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

(Not Applicable)

BACKGROUND OF THE INVENTION

Embedded or enclosed systems for housing electronic components, such asa computer chassis, that are designed to withstand high shock andvibration are well-known in the art. Exemplary of such prior-artenclosures include those environmental enclosures disclosed in U.S. Pat.Nos. 5,309,315 and 5,570,270, issued on May 3, 1994 and Oct. 29, 1996,respectively, to Nadell et al., entitled SEVERE ENVIRONMENT ENCLOSUREWITH THERMAL HEAT SINK AND EMI PROTECTION, the teachings of which areexpressly incorporated herein by reference. Additionally exemplary ofsuch prior-art apparatus include those enclosures disclosed in U.S. Pat.No. 5,381,314 issued on Jan. 10, 1995 to Rudy, Jr. et al., entitled HEATDISSIPATING EMI/RFI PROTECTIVE FUNCTION BOX, the teachings of which arelikewise incorporated herein by reference.

In this regard, such devices are typically designed to house computersystems for use in predominantly embedded applications in severeenvironments. With respect to the latter, it is well-recognized in theart that a severe environment is generally defined as one subject tolarge environmental extremes due to temperature, humidity, radiation,electromagnetic induction, shock and vibration. Additionally, anembedded application is generally accepted as meaning a specificfunction or functions, which are contained within a larger application,and requires no human intervention beyond supplying power to thecomputer. Exemplary of such embedded applications include systems andprocess controls, communications, navigations, and surveillance.

In order to properly function and perform such applications, it iscritical that the computer and other electronic components housed withinsuch enclosures be constructed, supported and enclosed in such a way asto be able to withstand such severe conditions. Along these lines, theprimary focus of such prior-art enclosures is to provide a structurallysound enclosure for an array of individual circuit boards or daughtercards in a backplane assembly to which the circuit boards areelectrically connectable and disconnectable, to thus define a card cage.

Despite the best efforts that can be made with respect to properlyarranging such circuit cards, however, an inherent problem in all suchembedded systems arises from the use of wiring between circuit cards,which is necessary to interconnect such circuit cards for data transfer.Specifically, hard-wired connections are known to become disconnectedwhen subjected to extremes in shock and vibration. In addition, becausemost prior art backplanes incorporate the use of a plurality of pins totransmit data between modules, there is thus increased the potential forelectrical connections to disconnect after repeated impact. Also, theuse of a plurality of pins can lead to an increase in energy consumed.

As such, there is a substantial need in the art for a system and methodfor operatively interconnecting a plurality of circuit cards with oneanother within an embedded system that can withstand severe environmentsto a greater degree than prior art system and methods. Likewise, thereis a substantial need in the art for such systems and methods that canproduce greater reliability, can be implemented utilizing existingtechnology, and allows for substantially more simplified circuitrydesign than prior art systems and methods.

BRIEF SUMMARY OF THE INVENTION

The present invention specifically addresses and alleviates theabove-identified deficiencies in the art. In this regard, the presentinvention is directed to systems and methods for interconnecting aplurality of modules, namely circuit boards or daughter cards, in anembedded environment that have increased reliability, can withstandshock and vibration, and provide greater electrical isolation betweensuch modules than prior art methods and systems.

In a preferred embodiment, the system comprises the use of astandardized infrared communication scheme, and in particular one ormore schemes developed by the Infrared Data Association, or IrDA, havingan electrical interface to transmit and receive data between modules. Inthis regard, each respective one of the plurality of modules comprisingan embedded computer system is provided with an IrDA electricalinterface to transmit and receive signals to thus provide a connectionbetween such modules.

Using an electrical interface implementation of IrDA provides for moresecure interconnection between modules than prior art hard-wiringtechniques, and further increases reliability by providing greaterredundancy (i.e., increasing the number of conductors used and availablefor transmitting the same data over multiple wires). The IrDA with anelectrical interface additionally provides for more secureinterconnection than conventional IrDA schemes by eliminating the needfor line-of-sight necessary for signals to be properly transported froma transmitter, typically an LED, to a receiver, the latter typically aphotodiode. The electrical interface further minimizes power consumptionby eliminating both the photodiode transceiver and LED componentstypically incorporated in most conventional IrDA schemes. Moreover, byutilizing infrared communication schemes, the systems and methods of thepresent invention can transmit data at high speed, which are currentlyknown in the art to function at 4 Mbps, and may eventually exceed 16Mbps.

It is therefore an object of the present invention to provide a systemand method for electrically interconnecting a plurality of circuit cardswith one another within an embedded system that can withstand severeenvironments to a greater degree than prior art system and methods.

Another object of the present invention is to provide a system andmethod for operatively interconnecting a plurality of circuit cards withone another with an embedded system that, in addition to being able towithstand severe environmental conditions, further minimizes powerconsumption.

Another object of the present invention is to provide a system andmethod for operatively interconnecting a plurality of circuit cards withone another within an embedded system that has greater reliability thanprior-art systems and methods, particularly with respect to performingdata transfer functions.

Another object of the present invention is to provide a system andmethod for operatively interconnecting a plurality of circuit cards withone another within an embedded system that are operative to facilitatehigh speed communication between system modules or circuit cardscontained within such system.

Still further objects of the present invention are to provide a systemand method for operatively interconnecting a plurality of circuit cardswith one another within an embedded system that is of simple and durableconstruction, relatively inexpensive to design and fabricate, may bereadily designed and implemented using conventional technology, and ismore effective and efficient than prior art systems and methods.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

These, as well as other features of the present invention, will becomemore apparent upon reference to the drawings, wherein:

FIG. 1 is an exploded view of an enclosure depicting a circuit cardpositionable therewithin.

FIG. 2 depicts a traditional IrDA setup that enables data to betransmitted and received between two modules via a transmission mediumof air.

FIG. 3 is block diagram of a proposed electrical interfaceimplementation of IrDA between two respective modules of an embeddedcomputer system that enables data to be transmitted and receivedtherebetween.

FIG. 4 is a block diagram of a second proposed electrical interfaceimplementation of IrDA between two respective modules of an embeddedcomputer system that enables data to be transmitted and receivedtherebetween.

DETAILED DESCRIPTION OF THE PRESENT EMBODIMENT

The detailed description as set forth below in connection with theappended drawings is intended as a description of the presentlypreferred embodiments of the invention, and is not intended to representthe only form in which the present invention may be constructed orutilized. The description sets forth the functions and sequences ofsteps for constructing and operating the invention in connection withthe illustrated embodiments. It is understood, however, that the same orequivalent functions and sequences may be accomplished by differentembodiments and that they are also intended to be encompassed within thescope of this invention.

Referring now to the figures, initially to FIG. 1, there is shown anexploded view of an environment enclosure 10 for housing a computersystem for use in running embedded applications in severe environments.As is well-known to those skilled in the art, such enclosures 10 arecapable of withstanding extreme environmental conditions, such asmaximum extremes of shock, vibration, temperature, EMI, humidity, aswell as sand, dust, and the like. Such containers are particularlyeffective in running embedded applications, which are defined as aspecific function which is contained within a larger applicationrequiring no human intervention beyond supplying power to the computer(not shown) housed therewithin. For example, embedded applicationsinclude but are not limited to, systems and process control,communications, navigation, and surveillance.

The computer systems utilized to run such applications typicallycomprise a plurality of circuit boards or daughter cards, such as 12,that are affixed about a backplane 16 rigidly mounted within theenclosure. In this respect, the backplane is provided with a pluralityof connectors 18 for supporting a plurality of circuit cards in agenerally parallel, upright relationship. The backplane 16 also supportsthe power supply (not shown), which is typically located within suchenclosure 10, to thus provide power for the computer system to function.

In prior art systems, the circuit cards are typically hard wired to oneanother, typically through a large number of conductors or pins, toenable data to be transmitted and received therebetween. The use ofhard-wire electric connections, however, is known to have severaldrawbacks. In this regard, hard wiring is known to be unreliable,particularly when subjected to severe shock and vibration insofar assuch forces cause the wire connections between circuit cards to break.

To address such problems, there is provided herein a novelcommunications scheme by which circuit cards can be interconnected toone another to transmit and receive data that eliminates the foregoingdrawbacks. In this respect, there is provided herein an infraredcommunications scheme utilizing an electrical interface thatinterconnects the plurality of circuit cards of an embedded computersystem to thus enable data to be received and transmitted therebetween.In this respect, each respective one of the plurality of the circuitcards is provided with a dedicated pair of buffered digital transceiverselectrically connected to one another that enable data signals to betransmitted and received therebetween.

The infrared communications scheme utilized in the present invention maytake any of a variety of the standard infrared protocols developed bythe Infrared Data Association, also known as IrDA. As is well-known tothose skilled in the art, the IrDA has created interoperable, low-costinfrared data interconnection standards that support a broad range ofapplications for use in computing and communications devices. Atraditional IrDA setup is depicted in FIG. 2 which, in simplified form,illustrates the ability to transmit and receive data between modules,via an air medium. As illustrated, a first module A, referred to as 20,is provided with an LED 22 for transmitting optical signals and aphotodiode 24 for receiving optical signals. A second module B, referredto as 26, is provided that likewise has an LED 28 and photodiode 30formed thereon. As is well known, the LED's and photodiodes respectivelyformed on each module enable data to be transmitted optically.

Advantageously, IrDA standards are ideally recommended for high speed,short range, line of sight, point-to-point cordless data transfer, whichare typically utilized in a widespread commercial applications forpersonal computers, digital cameras, hand-held data collection devices,and the like. A more detailed outline of the standards and protocolsdesigned and developed by the IrDA may be obtained from the InfraredData Association based in Walnut Creek, Calif. Alternatively, such datamay be obtained via the IrDA's website at http:\\www.irda.org\standards\standards.asp, the teachings of which are expressly incorporated hereinby reference.

As will be appreciated by those skilled in the art, the use ofstandardized IrDA infrared communications schemes currently can enabledata to be received and transmitted at rates up to four megabytes persecond (4 Mbps), which is substantially equivalent, if not faster, thanconventional hard-wired systems. It is further contemplated thatdevelopments may soon be made which can support data transfer rates inexcess of sixteen megabytes per second (16 Mbps).

As will further be appreciated by those skilled in the art, likewise theinfrared communications schemes developed by IrDA enable data tolikewise be transmitted and received via an electrical interface. Aswill be appreciated by those skilled in the art, the electricalinterface eliminates the need for line-of-sight alignment between LEDand photodiodes particularly utilized in IrDA schemes, and likewiseminimizes power consumption, which are known to be high in conventionalIrDA schemes when transmitting signals via LED transmitters.

Because of the single wire connections utilized, the electricalinterface implementation of IrDA allows a redundancy of connectionswhich may thus be utilized to transmit the same data over multipleconfigurations, discussed more fully below. As such, due to theincreased probability or the chance of a correct transmission, the IrDAelectrical interface implementation will have substantially increasedreliability as compared to conventional single line hard-wireconnections, which are known to deteriorate and eventually becomedisconnected when subjected to high shock or vibrational activity.

Given the widespread availability of IrDA standards and protocols, itwill be readily appreciated by those skilled in the art that a varietyof infrared communication schemes and the ability to electricallyinterface the same are already commercially available that may beimplemented to facilitate the transfer of data amongst circuit cards. Assuch, one skilled in the art would easily be able to pick and choosewhich particular IrDA infrared communication scheme may be appropriatefor a given application.

FIG. 3 depicts an example of how one such possible physicalimplementation of an IrDA infrared communications scheme may beimplemented according to a preferred embodiment of the presentinvention. As illustrated, first and second modules 40, 42 representingcircuit boards, daughter cards, and the like, having dedicated pairs ofdigital transceiver 44, 46, and 48, 50 formed thereon that areelectrically interfaced to one another such that each respective digitaltransceiver pair 44, 46, and 48, 50 is operative to transmit and receivedata from one module to another.

FIG. 4 depicts a second example of how an IrDA electrical interface maybe implemented according to a preferred embodiment of the presentinvention. As illustrated, first and second modules 60, 62 representingcircuit boards are provided that each include two output-transmittingtri-stateable digital buffers, 64 and 68 on first module 60, and 74, 78of second module 62, and two input or digital receivers 66 and 70 onfirst module, and 72 and 76 on second module 62. The respective pairs ofbuffers and receivers 64, 66, and 68, 70 on first module 60 and 72, 74,and 76, 78 on second module 62, are arranged such that each respectiveoutput or transmitter element is electrically interconnected to arespective input or receiver element formed on the respective othermodule.

Control is invoked over each transmitter element pair 44, 50 or 64, 74or 68, 78 such that they are prevented from transmitting simultaneouslyand thus contending for access to the same physical line. This controlis implemented via the tri-state control input on each transmitterelement. The media access control logic inherent to the IrDA protocolhandles collision detection and trys on a given data line.

By so arranging the transmitting and receiving elements in the mannershown, at least two connections are established through which data maybe transmitted and received between modules 60, 62. As such, to theextent a given connection between a respective transmitter element forexample 64 on first module 60, to receiver 72 on second module 62becomes disconnected or is otherwise not operative, there is yet asecond link, defined by transmitter element 68 of first module 60 toreceiver element 74 of second module 62, which can be utilized totransmit the same data. As will be appreciated by those skilled in theart, by providing such redundancy of interconnections, there is thusprovided a higher degree of reliability insofar as interconnectionbetween modules is not dependant upon a single connection. Likewise,because conventional hard-wiring systems already taken into accountnumerous conductors, typically formed as pin-type connections, iscurrently believed that the electrical interface implementation of IrDAwould, at a minimum, be equivalent to prior art hard-wire connections,and thus would not be spatially inhibiting.

It is to be further understood that various additions, deletions,modifications and alterations may be made to the above-describedembodiments without departing from the intended spirit and scope of thepresent invention. Accordingly, it is intended that all such additions,deletions, modifications and alterations be included within the scope ofthe following claims.

1. A shock-resistant system for operatively interconnecting modules within a computer system to enable data to be transmitted and received therebetween comprising: a. a first module having a first media access control logic circuit for transmitting and receiving data substantially conforming to a standardized infrared communications scheme protocol; b. a second module having a second media access control logic circuit for transmitting and receiving data substantially conforming to said standardized infrared communications scheme protocol utilized by said first module; and c. a single hardwired electrical conductor signal path connecting said first and second modules to facilitate electrical bi-directional communications between said first and second media access control logic circuit only through said hardwired electrical conductor signal path; wherein said system comprises a multiplicity of modules, wherein each respective one of said multiplicity of modules comprises at least one dedicated transmitter element and receiver element within said module, each respective one of said multiplicity of modules being electrically interfaced to one another via said transmitter and receiver elements such that said modules are operative to transmit and receive data therebetween.
 2. The system of claim 1 wherein said infrared communications scheme protocol comprises a protocol developed by the Infrared Data Association.
 3. The system of claim 1 wherein said first and second modules are housed within an enclosure.
 4. The system of claim 1 wherein said first and second modules are operative to run an embedded application.
 5. The system of claim 1 wherein said modules comprise of at least one of an individual circuit board and a daughter card.
 6. The system of claim 1 wherein the at least one transmitter element comprises a tri-stateable digital transmitter and the at least one receiver element comprises a tri-stateable digital receiver.
 7. A method for operatively interconnecting modules within a computer to enable data to be transmitted and received therebetween comprising: a. providing a first module having a first media access control logic circuit including at least one dedicated transmitter and receiver element for transmitting and receiving data substantially conforming to a standardized infrared communications scheme protocol; b. providing a second module having a second media access control logic circuit including at least one dedicated transmitter and receiver element for transmitting and receiving data substantially conforming to a standardized infrared communications scheme protocol; c. forming a single hardwired electrical conductor signal path solely connecting the first and second media access control logic circuits such that the first and second modules are interfaced to each other via the at least one transmitter and receiver elements, allowing the first and second modules to transmit and receive data therebetween; and d. communicating electrically between the first and second modules only through said single hardwired electrical conductor signal path bi-directionally using the standardized infrared communications scheme protocol.
 8. The method of claim 7 wherein in steps a) and b), said infrared communications scheme protocol comprises a protocol developed by the Infrared Data Association.
 9. The method of claim 7 wherein in steps a) and b), said first and second modules are housed within an enclosure.
 10. The method of claim 7 wherein in step c), said first and second modules are operatively coupled to run an embedded application.
 11. The method of claim 7 wherein the at least one transmitter element comprises a tri-stateable digital transmitter and the at least one receiver element comprises a tri-stateable digital receiver.
 12. A vibration-resistant system for interconnecting modules within a computer system enabling data to be reliably transmitted and received therebetween comprising: a. a first module having a first media access control logic circuit including a dedicated transmitter and receiver element for transmitting and receiving data conforming to a standardized infrared communications scheme protocol; b. a second module having a second media access control logic circuit including a dedicated transmitter and receiver element for transmitting and receiving data conforming to the standardized infrared communications scheme protocol utilized by the first module; and c. a single hardwired electrical conductor signal path connecting the first and second modules to facilitate electrical bi-directional communications between the first and second media access control logic circuits, wherein the first and second modules are interfaced to each other via respective transmitter and receiver elements such that the first and second modules are operative to transmit and receive data therebetween through the single hardwired electrical conductor signal path.
 13. The system of claim 12 wherein the infrared communications scheme protocol comprises a protocol developed by the Infrared Data Association.
 14. The system of claim 12 wherein the first and second modules are housed within an enclosure.
 15. The system of claim 12 wherein the first and second modules are operative to run an embedded application.
 16. The system of claim 12 wherein the transmitter elements comprise tri-stateable digital transmitters and the receiver elements comprise tri-stateable digital receivers.
 17. A vibration-resistant system for interconnecting modules within a computer system enabling data to be reliably transmitted and received therebetween comprising: a. a first module having a first media access control logic circuit including a plurality of pairs of transmitter and receiver elements for transmitting and receiving data conforming to a standardized infrared communications scheme protocol; b. a second module having a second media access control logic circuit including a plurality of pairs of transmitter and receiver elements for transmitting and receiving data conforming to the standardized infrared communications scheme protocol utilized by the first module; and c. a plurality of hardwired electrical conductor signal paths connecting the first and second modules, each hardwired signal path interfaced between respective pairs of transmitter and receiver elements from the first and second modules to facilitate electrical bi-directional communications between the first and second media access control logic circuits; wherein the plurality of hardwired electrical conductor signal paths and respective pairs of transmitter and receiver elements from the first and second modules provide a plurality of redundant data links between the first and second modules such, that the modules are operative to transmit and receive data therebetween when a failure occurs in one of the plurality of redundant data links.
 18. The system of claim 17 wherein the transmitter elements comprise tri-stateable digital transmitters and the receiver elements comprise tri-stateable digital receivers.
 19. A method for interconnecting modules within a computer in a redundant manner enabling data to be reliably transmitted and received therebetween comprising: a. providing a first module having a first media access control logic circuit including a plurality of pairs of transmitter and receiver elements for transmitting and receiving data conforming to a standardized infrared communications scheme protocol; b. providing a second module having a second media access control logic circuit including a plurality of pairs of transmitter and receiver elements for transmitting and receiving data conforming to the standardized infrared communications scheme protocol utilized by the first module; c. providing a plurality of hardwired electrical conductor signal paths connecting the first and second modules, each hardwired signal path interfaced between respective pairs of transmitter and receiver elements from the first and second modules to facilitate electrical bi-directional communications between the first and second media access control logic circuit; and d. communicating electrically between the first and second modules through one of the plurality of hardwired electrical conductor signal paths bi-directionally using the standardized infrared communications scheme protocol; wherein the plurality of hardwired electrical conductor signal paths and respective pairs of transmitter and receiver elements from the first and second modules provide a plurality of redundant data links between the first and second modules such that the modules are operative to transmit and receive data therebetween when a failure occurs in one of the plurality of redundant data links.
 20. The method of claim 19 wherein the transmitter elements comprise tri-stateable digital transmitters and the receiver elements comprise tri-stateable digital receivers. 